WATER PUMP

[bcmc33]

As a matter of academic interest - where exactly should the impeller be in relation to the joint between the timing case back plate and the block?
Does ? a couple of millimetres make that much difference?

[CBUEB1771]

As a matter of academic interest - where exactly should the impeller be in relation to the joint between the timing case back plate and the block?
Does ? a couple of millimetres make that much difference?

Per the workshop manual the gap between the impeller blade tips and the insert with the two o-ring grooves is to be 0.02" to 0.03" (.51 mm to .76 mm). I have found this to be a bit difficult to measure because you have to squeeze the insert into the front cover while fiddling with a wire gauge. This is best done before fitting the o-rings to the insert. It is a sloppy tolerance. Pumping efficiency would improve by reducing this gap. I aim for the lowest value in the ranges given.

[Crusty]

Out of intrest how much play should there be on the hub of the water pump. Example by holding the end of the cooling fan how far should it move in relation to water pump fatigue. Would a newley installed pump not move at all.??

[billwill]

In my experience it should not move at all.

The bearing is a tight fit in the front timing case and then there is a round wire spring clip which locks the bearing in so that it cannot work out at all. the clearance around this clip in the outer of the bearing and the groove on the inside of the bearing hole, I would guess is only about one or two thou.

The shaft in a bearing in good condition will not move along the shaft dimension, if it does the balls or rollers inside are rusted and worn down.

Check that the bolts holding the pulley to the flange are tight, your movement might be the pulley w.r.t the flange.

[UAB807F]

Ditto above. I've just fitted a new pump over winter and grasping the hub itself there's no movement at all, rock solid.

The old pump had a slight movement although only a few thou' but as stated above, the bearings were worn & rusty. Although that wasn't the main reason for replacement, it was the mechanical seal failing when starting after a prolonged period of "resting".

As for the original question, I set the clearance on mine to 0.020" & it seems to be operating fine.

[billwill]

Checking the service manual I see that the bearing is a PRESS fit into the timing case, which brings to mind that you must NOT press this in by pressing on the shaft, because if you do so you are putting a sideways force on the balls or rollers inside the bearing and you can wreck them before you even start using that new pump kit.

You have to get or make a tube that presses the OUTER of the bearing.

[bcmc33]

Over 270 views and no attempt to answer my question - so I am bound to assume no-one knows the answer.

[billwill]

? I thought you got your answer in the first reply.

Boils down to: as close to the insert as you can make it provided that it doesn't touch.

Why do you want to measure it relative to the back plate?

[bcmc33]

? I thought you got your answer in the first reply.

Boils down to: as close to the insert as you can make it provided that it doesn't touch.

Why do you want to measure it relative to the back plate?

So you really did understand my question, Bill - and your reply shows I didn't get an answer.

To repeat myself, it is only the position of the impeller to the plate/block line that I am interested in.

I have made my own cartridge pump assembly by converting the standard timing case and backplate and making a two piece cartridge and a standard pump kit. I made this with the cartridge ending at the plate/block line, as per the standard set-up, and the impeller set at 10 thou in the standard position.
I have designed a new cartridge method that I've now found out that closely copies the Burton design, and before making it I wondered if I could improve the performance by changing the position of the impeller.
Thought process: In the standard impeller position the block wall thickness is about 4mm thick and effectively blocks part of the impeller blades - if the cartridge is made 4mm longer the whole impeller would be inside the block - would this improve the water flow around the system?
Conversely, if the cartridge was say 1-2mm shorter, would this significantly reduce flow performance compared to the standard set-up? (I have a good reason to ask this question).

[billwill]

Unfortunately no-one is likely to have your answer since it requires that they have in hand a fully assembled front of a timing case and a back plate off the engine on hand. Most owners only take the front off to fit a new water-pump.

If you ask instead what is the distance from the back of the impellor to the back surface of the front of the timing case, you might get an answer from anyone who currently has a pump fitting in progress, then you can add on the thickness of the centre boss of the back plate (which is appx 11.5 mm).

I'd give you an answer if I could, but the timing case I have in my hand here has no water-pump in it. and I won't be fitting one as the case is being sold to James.

[bcmc33]

Unfortunately no-one is likely to have your answer since it requires that they have in hand a fully assembled front of a timing case and a back plate off the engine on hand. Most owners only take the front off to fit a new water-pump.

If you ask instead what is the distance from the back of the impeller to the back surface of the front of the timing case, you might get an answer from anyone who currently has a pump fitting in progress, then you can add on the thickness of the centre boss of the back plate (which is appx 11.5 mm).

I'd give you an answer if I could, but the timing case I have in my hand here has no water-pump in it. and I won't be fitting one as the case is being sold to James.

Bill,
Clearly I'm not expressing myself very well as your latest reply still does not address my question.
I have all the necessary dimensional information on the timing case, plate and standard pump.

I am after some informed information that may be out there regarding the criticality of the impeller in relation to the plate/block position and flow performance.
It is not something that I've given two seconds thought to over the past 40 years of fitting standard pump kits, but now I've started to work on cartridge set-ups, I think there is the possibility that it offers the potential to improve the flow that has always been considered a little marginal in these high performance engine.

My first cartridge turned-out to be a close copy of the Dave Bean set-up, and I made it as per standard with the impeller being virtually in line with the plate/block joint line.
Now I'm going to make what looks suspiciously like the Burton design, I had the thought that perhaps I could improve the flow by placing the impeller further into the block by making the cartridge longer - maybe by 4-5mm as long as it does not foul the casting.

I'm sure the Dave Bean and Burton design teams have given this subject some consideration before producing their products, it's just that I thought that there may be some informed people out there that can put be straight on this subject.

Fishing I call it.

[Elanman99]

[quote="bcmc33"][quote="billwill"]Unfortunately no-one is likely to have your answer since it requires that they have in hand a fully assembled front of a timing case and a back plate off the engine on hand. Most owners only take the front off to fit a new water-pump.

If you ask instead what is the distance from the back of the impeller to the back surface of the front of the timing case, you might get an answer from anyone who currently has a pump fitting in progress, then you can add on the thickness of the centre boss of the back plate (which is appx 11.5 mm).
[/quote]
Bill,
Clearly I'm not expressing myself very well as your latest reply still does not address my question.
I have all the necessary dimensional information on the timing case, plate and standard pump.

I am after some informed information that may be out there regarding the criticality of the impeller in relation to the plate/block position and flow performance.
It is not something that I've given two seconds thought to over the past 40 years of fitting standard pump kits, but now I've started to work on cartridge set-ups, I think there is the possibility that it offers the potential to improve the flow that has always been considered a little marginal in these high performance engine.

My first cartridge turned-out to be a close copy of the Dave Bean set-up, and I made it as per standard with the impeller being virtually in line with the plate/block joint line.
Now I'm going to make what looks suspiciously like the Burton design, I had the thought that perhaps I could improve the flow by placing the impeller further into the block by making the cartridge longer - maybe by 4-5mm as long as it does not foul the casting.

I'm sure the Dave Bean and Burton design teams have given this subject some consideration before producing their products, it's just that I thought that there may be some informed people out there that can put be straight on this subject.

Fishing I call it.[/quote]

I think one reason that you might not be getting the answer you are looking for is because without the parts in hand (or dimensioned/sectional drawings) is that you are trying to establish a dimension between a point that you define well (the block front face) and the impellor which is about 20mm thick (from memory) so its a bit imprecise .

If you are using the standard pump kit of parts then you do not have that much leeway in relocating the impellor because you still want the pulley to stay in the same place.

If the object of the exercise is to improve the pump performance then it might be better to use a different pump altogether.!

Ian P

[bcmc33]

I think one reason that you might not be getting the answer you are looking for is because without the parts in hand (or dimensioned/sectional drawings) is that you are trying to establish a dimension between a point that you define well (the block front face) and the impellor which is about 20mm thick (from memory) so its a bit imprecise.

It's precision engineering - there's nothing imprecise about the impeller or any of the associated parts.

If you are using the standard pump kit of parts then you do not have that much leeway in relocating the impellor because you still want the pulley to stay in the same place.

On all the kits I've bought there is at least 5mm spare shaft at the impeller end. That's one of the points that gave me the idea to move the impeller.

If the object of the exercise is to improve the pump performance then it might be better to use a different pump altogether.

Not if there is a simple answer with the the bits I have around me now.
However, if there was adequate room I would have fitted an electric pump long ago.


I had hoped that the point of my question would have sparked some enlightened and informed engineering comment, positive or negative - perhaps the people I was looking for are on vacation.

[rgh0]

Hi Brian

Ideally the stator that the face of the impellor runs against would be inserted fully into the block itself so you have the tips of the impellor fully open to discharge water into the water jacket and a streamline curve of the stator along the full face of the impellor.

However the tolerances of the assembly made achieving this in practice difficult for it to fit in the block opening so it was stopped at the face of the block in the orginal design and in both the Burton and DB redesigns.

You are also limited in how far the impellor can move back without hitting the outer wall of the no1 cylinder bore casting.

Moving the impellor and stator further forward would increase the shrouding of the impellor tips with the block wall and not be desirable.

I have seen impellors of slightly different sizes and thickness and blade heights over the years depending on their source and maybe some are better than others as some reach slightly further back into the block but hard to tell without proper testing rigs to compare actual pump curve performance.

I would stick with the standard impellor location unless you have a specific reason to try a change.

cheers
Rohan

[billwill]

I'm inclined to think that creating an impellor with smooth curved fins would have advantages that well outweighed designing it to be a bit further back.

Difficult to cast such an impellor in one piece though, so that is probably why the standard one has straight fins.